How Many Batteries On Your Boat and Why do I have 4 ?

pistole

hi fellas. On my 330 , I see 4 batteries in the engine compartment. Is this normal ? How many batteries are required in a twin engine setup ? Thanks.

Michael T

On my EC 360 I had two series 31 AGM 1000 CA - one for each engine (plus generator used one to start) and three series 31 AGMs properly wired for the house batteries. Where I bought them there was little price difference to up-grade to the series 31 but the 31s had (IMO) quite an advantage regarding  reserve minutes capacity, AHs, and cranking amps. If I were to do it now it would be TPPL (thin plate pure lead) AGMs.

pistole

Michael T said:

On my EC 360 I had two series 31 AGM 1000 CA - one for each engine (plus generator used one to start) and three series 31 AGMs properly wired for the house batteries. Where I bought them there was little price difference to up-grade to the series 31 but the 31s had (IMO) quite an advantage regarding  reserve minutes capacity, AHs, and cranking amps. If I were to do it now it would be TPPL (thin plate pure lead) AGMs.

so you had 5 batteries in total ?

Willhound

My buddy who regularly anchors out for days at a time up on Georgian Bay has 6.
Two for starting and 4 for house use. All professionally wired and you need an operator's manual for the battery switch configurations.

Liberty44140

Your configuration is normal, on my 342 I have 2 group 24 for starting and 2 group 29 for house 

reneechris14

Your 2 cranking batteries are isolated to the motors only the house batteries is what your draw off all day (mostly the fig.) So if you don't anchor out 1 is ok, anchor out for 36 hours 2 are ok, any longer you need a genny or more battery. Some sailboats have 6 or a couple really big ones.

Stodge

I have all group 31, same config, 1 port start, 1 starboard start, 2 house.

rinker270nb

If you turn the accessory key, aka radio, does the draw come from the starter (engine) battery or house battery?  

MarkB

Yes, 4 is normal. One for each engine (cranking), and 2 others for house.

reneechris14

rinker270nb said:

If you turn the accessory key, aka radio, does the draw come from the starter (engine) battery or house battery?  

On the 270 you have 2 batteries what ever the switch is on is the you are drawing off 

LaRea

rinker270nb said:

If you turn the accessory key, aka radio, does the draw come from the starter (engine) battery or house battery?  

Your stereo won't kill your starter batteries.

The radio draws only a tiny current from the ignition circuit.  It's just a few milliamps telling the amplifiers to turn on.  The amplifiers, which draw much more current, draw directly from the house bank.

reneechris14

That is true forgot about the amp. That LeRay guy is very intelligent.

Dream_Inn

reneechris14 said:

That is true forgot about the amp. That LeRay guy is very intelligent.

I agree, but that Chris guy needs to learn to spell his name!

reneechris14

I no eye speel lik krap.

bobmcl73

do you have to use the same group #batteries? because group d27 deep cycle marine batteries seem to have the same external dimensions? what is the differences?

Liberty44140

Difference is cranking amps and starter vs deep cycle. My 342 only needed group 24 for starting so I had two 24s for starting and then two 29s for house. You really will want to stick with at least 27s for the house but since 29s fit in the 27 box it’s worth another $20 per battery. Many would recommend 31 for house which will get you more amps of power for another $40 or so per battery. 

You want starting batteries for engines and deep cycle for house. There are dual purpose out there as well. 

LaRea

@bobmcl73 - the group number refers to the size and shape of the battery.  The important number for starter batteries is MCA - marine cranking amps.  Which engine(s) do you have?  I have big-block Mercruiser 496 engines, and Merc recommends 800 MCA for the starters.  

For house batteries, most people want as much capacity as they can get.  It's only limited by available space and budget.